• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.1-12
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• 1997

The acousto-optical spectrometer as a new type backend of the receiver system for radio astronomical observations is manufactured for radio signal analysis. We studied on the effect of Acousto-Optic and Acousto-Optic devices and designed the optics system. We manufactured the optical mount and the CCD detector for deflected beam and interface card. This acousto-optical spectrometer consisted of a laser, optics, acousto-optic deflector, CCD detector and Interface card. This system use He-Ne laser as a light source and use optics to get parallel beam and to focus the deflected beam. Acousto-optic deflector converts IF signal to ultrasonic wave and deflect the laser beam according to the Bragg deflection. The ultra wide band acousto-optic deflector has 1 GHz bandwidth and a total of 2,048 channel Charge Coupled Device for signal detection. In this study, we discuss the theoretical description on the effect of Acousto-optics, the design of the optics, manufacture of optical mount, CCD detector, interface card and we presented the results of experiment. As a result of measurement, we have 1,000 channels bandwidth from CCD channels.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.17-22
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• 2018

Multilayer mirrors are optical elements that can replace single crystal optical elements such as silicon or germanium, and they have artificial diffraction plane of a thickness of several nanometers. We examined the first Bragg angle and the reduction of reflectivity by variation of layer thickness in a W/Si multilayer mirror of small d-spacing. A W/Si multilayer mirror for an incidence angle of $0.55^{\circ}$ and an energy of 17.5 keV was designed and showed a maximum reflectivity of 72.67%. When the thickness of tungsten or silicon layer was simultaneously changed, the first Bragg angle was shifted and the reflectivity was reduced. When there was a change in thickness for one layer of W/Si multilayer, no change in the reflectivity was showed but the unevenness of the envelope was observed. Reduction of reflectivity was also observed at random Gaussian thickness variations. It is possible to predict the tolerance of multilayer mirror by examining the reflectivity degradation according to the thickness change in the W/Si multilayer mirror of small d-spacing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1810-1817
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• 2004

A diffractive optical element(DOE) for an optical pickup system is proposed in this thesis. Optimization algorithms are used to synthesise the DOE to meet a detailed specification of the two kind of cost function. The one isso called as apodization which refers to the process of suppressing the secondary maxima and the other is so called as sharpness which refers to the process of reducing the size of primary maxima. The result obtained by simplex optimization method is that the apodization and sharpness are well achieved separately. In apodization, the secondary maxima is reduced up to 39%. And in sharpness, the size of first maxima is reduced to 95.2％.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.192-197
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• 1993

반도체 기억소자의 급격한 발전추세에 대응하기 위해서는 노광(exposure) 장비의 증첩정밀도 (overlay accuracy)가 같이 개선되어야 한다. 본 연구에서는 64M ERAM 제조를 목적으로개발된 스텝 퍼(stepper) 시스템의 성능평가 항목 중에서 증첩정밀도에대한 측정방법 및 현재까지의 연구결과를 기술하였다. 제작된 웨이퍼 정렬계는 off-axis 및 TTL 광학계와 이들 정렬신호에 따라 움직이는 웨이 퍼 구동계로 구성되어 있다. off-axis 광학계는 화상처리와 회절의 두 가지 방식이 가능하도록 설계 제작되었으며, TTL 광학계는 dual beam interferometric method를 이용하였다. 본 실험의 결과는 웨이퍼 정렬계의 특성을 평가한 것으로서, 현재까지 off-axis 정렬 방법만으로 얻은 증첩정밀도는 0.26-0.29$\mu$m (m+3 $\sigma$ )이다. 따라서 여기에 이미 제작되어 있는 TLL 정렬광학계를 추가로 사용하면 0.1 $\mu$m 이하의 정밀도에 이를 것으로 예측된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.965-967
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• 2003

Czochralski pulling method에 의해 성장된 고농도 도핑 Nd:LSB의 광학적 특성을 조사하였다. 결정 성장조건에 의해 달라지는 space group은 지금까지 C2/c, R32, Cc와 C2등 4가지가 보고되었으며, 기본적으로 6방정계의 구조를 가지고 비선형 광학 결정으로서의 특성을 보였다. x선 회절 분석계를 이용하여 구조를 분석하였고, 도핑 농도에 따른 형광 수명의 변화, 분산곡선 특성을 조사하였다. 또한 흡수 및 저온 형광 스펙트럼을 이용하여 도핑 농도 및 space group의 변화에 따른 에너지 준위의 변화를 관찰하고 비교하였다.

• Korean Journal of Optics and Photonics
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• v.2 no.4
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• pp.193-196
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• 1991

Reflection holographic filters are developed. Dichromated gelatin films are used for the recording material, and a modified processing method of obtaining high-quality filters is developed. The diffraction efficiency and bandwidth of the fabricated holographic filter is 93% and 17 nm, respectively. The effect of exposure on the spectral bandwidth and center wavelength of the developed filters are measured, and the characteristics of the dichromated gelatin film are investigated from these results.

• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.101-107
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• 1995

To investigate the diffraction property of the Bessel beam for defocus which acts CFAP (Combined Filter of Amplitude and Phase), we calculated numerically the intensity, the radius of central spot, and the optical transfer function for the number of node of the Bessel beam when an optical system has an aberration-free or a spherical aberration. The Bessel beam has larger the maximum intensity and the OTF value for an optical system with a spherical aberration than that with an aberrationfree. Particularly, the OTF value at the point of maximum intensity for $W_{40}=3\lambda$is higher for the Bessel beam than for the Clear aperture. From these results, we know that the Bessel beam has the compensating effect. The Bessel beam also has the radius of central spot having a superresolution. We will useful for the fabrication of semiconductor device and the optical recording system using these effects.ffects.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.474-474
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• 2013

PDMS는 미세패턴을 위해 소프트 리소그래피 널리 활용되어질 뿐만 아니라, 재질이 투명하고 탄성과 강한 내구성을 갖고 있어 유연한 광학 및 전자소자에 이용될 수 있다. 최근에는, 이러한 PDMS를 서브파장구조(subwavelength grating structure)를 형성하거나 텍스쳐(texture)표면구조를 이용한 효과적인 반사방지막(antireflection coating)기판을 제작하여 태양전지 및 디스플레이 소자의 성능을 발전시키는 연구가 활발히 진행되고 있다. 한편, 수열합성법(hydrothermal method)이나 전기화학증착법(electrodeposition method)으로 비교적 간단한 공정을 통해서 다양한 기판위에 산화아연(ZnO) 나노막대(nanorod)를 수직정렬로 성장시킬 수 있는데, 이러한 구조는 반사방지특성의 유효 굴절률 분포(effective refractive index profile)를 갖고 있기 때문에 LED나 태양전지에 성능을 개선할 수 있다. 이에 본 연구에서는 수열합성법을 통해 성장된 수직 정렬된 산화아연 나노막대를 이용한 PDMS 표면의 미세패턴 형성하여 광학적 특성을 분석하였다. 실험을 위해, 스퍼터링을 통해서 산화아연 시드층을 형성한 후, 질산아연헥사수화물과 헥사메틸렌테트라민을 수용액에 담가두어 산화아연 나노막대를 성장시켰으며, PDMS의 베이스와 경화제의 질량비를 10：1으로 용액을 준비하여 수직 정렬된 산화아연 나노막대 표면을 casting method으로 코팅하여 열경화 처리하였다. 제작된 샘플의 형태, 구조 광특성을 관찰하기 위해서 전계방출형전자현미경, X선 회절 분석기, 분광 광도계를 이용하였다.

• Korean Journal of Optics and Photonics
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• v.23 no.4
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• pp.135-142
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• 2012

We have developed a measurement method of the refractive index profile of an optical fiber by using diffraction phase microscopy. In the microscope system, the reference light was extracted directly from the probe light that passed through the sample by means of pinhole filtering with a diffraction grating. The spatial interference pattern produced by the probe light and the reference light was processed to generate the phase image of the sample fiber. The index profile was obtained by the inverse Abel transform of the phase profile. In order to remove the background phase that originated from the index difference between the cladding and the surrounding medium, the background phase was calculated from the phase data of the cladding to make a core phase profile that can be directly transformed to the index profile of the core without the full phase image that includes the entire cladding part.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.386-390
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• 1999

Erasable polarization holographic grating was recorded with two-wave mixing in PCN which was side-chain liquid crystalline polymalonic esters containing two symmetrical 4-cyanoazobenzene as photoresponsive groups. The diffraction efficiency of recorded grating was measured and the characteristics of recording, decay in a dark room and erasing by circularly polarized light were investigated. As the results, birefringence, $\Delta$n of PCN was measured $6.5{\times}10^{-2}$, which was 0~100 times higher than those of crystals such as Fe:$LiNbO_3$, Ce:$BaTiO_3$ crystals. Dark decay rates was $4.3{\times}10^{-5}$ %/hour, which showed the possibility of application as data storage media.